Look for first-parent commits in the remote branch of interest and add more logging

Also do not need depot_tools checkout for android rools.

BUG=skia:6533

Change-Id: Icf91d5b33eb9f2819b444c50dd0aae9dc3b3da5a
Reviewed-on: https://skia-review.googlesource.com/14362
Commit-Queue: Ravi Mistry <rmistry@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
diff --git a/autoroll/go/autoroll/main.go b/autoroll/go/autoroll/main.go
index 81985be..fd964a2 100644
--- a/autoroll/go/autoroll/main.go
+++ b/autoroll/go/autoroll/main.go
@@ -273,9 +273,12 @@
 	sklog.Infof("Sheriff: %s", strings.Join(emails, ", "))
 
 	// Sync depot_tools.
-	depotTools, err := depot_tools.Sync(*workdir)
-	if err != nil {
-		sklog.Fatal(err)
+	var depotTools string
+	if !*rollIntoAndroid {
+		depotTools, err = depot_tools.Sync(*workdir)
+		if err != nil {
+			sklog.Fatal(err)
+		}
 	}
 
 	// Start the autoroller.
diff --git a/autoroll/go/autoroller/roller.go b/autoroll/go/autoroller/roller.go
index 36be84e..13d9a38 100644
--- a/autoroll/go/autoroller/roller.go
+++ b/autoroll/go/autoroller/roller.go
@@ -343,6 +343,7 @@
 		sklog.Infof("Roll succeeded (%d); syncing the repo until it lands.", currentRoll.Issue)
 		for {
 			sklog.Info("Syncing...")
+			sklog.Infof("Looking for %s", currentRoll.RollingTo)
 			if err := r.rm.ForceUpdate(); err != nil {
 				return err
 			}
diff --git a/autoroll/go/repo_manager/android_repo_manager.go b/autoroll/go/repo_manager/android_repo_manager.go
index e6c405f..434b694 100644
--- a/autoroll/go/repo_manager/android_repo_manager.go
+++ b/autoroll/go/repo_manager/android_repo_manager.go
@@ -178,7 +178,7 @@
 
 // getLastRollRev returns the commit hash of the last-completed DEPS roll.
 func (r *androidRepoManager) getLastRollRev() (string, error) {
-	output, err := exec.RunCwd(r.childRepo.Dir(), "git", "log", "--pretty=format:%H", "--no-merges", "-1")
+	output, err := exec.RunCwd(r.childRepo.Dir(), "git", "log", "--pretty=format:%H", "--no-merges", "-1", "--first-parent", fmt.Sprintf("refs/remotes/remote/%s", r.childBranch))
 	if err != nil {
 		return "", err
 	}